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                <ol class="chapter"><li class="chapter-item expanded affix "><a href="../翻译说明.html">翻译说明</a></li><li class="chapter-item expanded affix "><a href="../introduction.html">介绍</a></li><li class="chapter-item expanded "><a href="../notation.html"><strong aria-hidden="true">1.</strong> 表义符</a></li><li class="chapter-item expanded "><a href="../lexical-structure.html"><strong aria-hidden="true">2.</strong> 词法结构</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../input-format.html"><strong aria-hidden="true">2.1.</strong> 输入格式</a></li><li class="chapter-item expanded "><a href="../keywords.html"><strong aria-hidden="true">2.2.</strong> 关键字</a></li><li class="chapter-item expanded "><a href="../identifiers.html"><strong aria-hidden="true">2.3.</strong> 标识符</a></li><li class="chapter-item expanded "><a href="../comments.html"><strong aria-hidden="true">2.4.</strong> 注释</a></li><li class="chapter-item expanded "><a href="../whitespace.html"><strong aria-hidden="true">2.5.</strong> 空白符</a></li><li class="chapter-item expanded "><a href="../tokens.html"><strong aria-hidden="true">2.6.</strong> token</a></li></ol></li><li class="chapter-item expanded "><a href="../macros.html"><strong aria-hidden="true">3.</strong> 宏</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../macros-by-example.html"><strong aria-hidden="true">3.1.</strong> 声明宏</a></li><li class="chapter-item expanded "><a href="../procedural-macros.html"><strong aria-hidden="true">3.2.</strong> 过程宏</a></li></ol></li><li class="chapter-item expanded "><a href="../crates-and-source-files.html"><strong aria-hidden="true">4.</strong> crate 和源文件</a></li><li class="chapter-item expanded "><a href="../conditional-compilation.html"><strong aria-hidden="true">5.</strong> 条件编译</a></li><li class="chapter-item expanded "><a href="../items.html"><strong aria-hidden="true">6.</strong> 程序项</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../items/modules.html" class="active"><strong aria-hidden="true">6.1.</strong> 模块</a></li><li class="chapter-item expanded "><a href="../items/extern-crates.html"><strong aria-hidden="true">6.2.</strong> 外部crate</a></li><li class="chapter-item expanded "><a href="../items/use-declarations.html"><strong aria-hidden="true">6.3.</strong> use声明</a></li><li class="chapter-item expanded "><a href="../items/functions.html"><strong aria-hidden="true">6.4.</strong> 函数</a></li><li class="chapter-item expanded "><a href="../items/type-aliases.html"><strong aria-hidden="true">6.5.</strong> 类型别名</a></li><li class="chapter-item expanded "><a href="../items/structs.html"><strong aria-hidden="true">6.6.</strong> 结构体</a></li><li class="chapter-item expanded "><a href="../items/enumerations.html"><strong aria-hidden="true">6.7.</strong> 枚举</a></li><li class="chapter-item expanded "><a href="../items/unions.html"><strong aria-hidden="true">6.8.</strong> 联合体</a></li><li class="chapter-item expanded "><a href="../items/constant-items.html"><strong aria-hidden="true">6.9.</strong> 常量项</a></li><li class="chapter-item expanded "><a href="../items/static-items.html"><strong aria-hidden="true">6.10.</strong> 静态项</a></li><li class="chapter-item expanded "><a href="../items/traits.html"><strong aria-hidden="true">6.11.</strong> trait</a></li><li class="chapter-item expanded "><a href="../items/implementations.html"><strong aria-hidden="true">6.12.</strong> 实现</a></li><li class="chapter-item expanded "><a href="../items/external-blocks.html"><strong aria-hidden="true">6.13.</strong> 外部块</a></li><li class="chapter-item expanded "><a href="../items/generics.html"><strong aria-hidden="true">6.14.</strong> 泛型参数</a></li><li class="chapter-item expanded "><a href="../items/associated-items.html"><strong aria-hidden="true">6.15.</strong> 关联程序项</a></li></ol></li><li class="chapter-item expanded "><a href="../attributes.html"><strong aria-hidden="true">7.</strong> 属性</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../attributes/testing.html"><strong aria-hidden="true">7.1.</strong> 测试</a></li><li class="chapter-item expanded "><a href="../attributes/derive.html"><strong aria-hidden="true">7.2.</strong> 派生</a></li><li class="chapter-item expanded "><a href="../attributes/diagnostics.html"><strong aria-hidden="true">7.3.</strong> 诊断</a></li><li class="chapter-item expanded "><a href="../attributes/codegen.html"><strong aria-hidden="true">7.4.</strong> 代码生成</a></li><li class="chapter-item expanded "><a href="../attributes/limits.html"><strong aria-hidden="true">7.5.</strong> 极限值设置</a></li><li class="chapter-item expanded "><a href="../attributes/type_system.html"><strong aria-hidden="true">7.6.</strong> 类型系统</a></li></ol></li><li class="chapter-item expanded "><a href="../statements-and-expressions.html"><strong aria-hidden="true">8.</strong> 语句和表达式</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../statements.html"><strong aria-hidden="true">8.1.</strong> 语句</a></li><li class="chapter-item expanded "><a href="../expressions.html"><strong aria-hidden="true">8.2.</strong> 表达式</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../expressions/literal-expr.html"><strong aria-hidden="true">8.2.1.</strong> 字面量表达式</a></li><li class="chapter-item expanded "><a href="../expressions/path-expr.html"><strong aria-hidden="true">8.2.2.</strong> 路径表达式</a></li><li class="chapter-item expanded "><a href="../expressions/block-expr.html"><strong aria-hidden="true">8.2.3.</strong> 块表达式</a></li><li class="chapter-item expanded "><a href="../expressions/operator-expr.html"><strong aria-hidden="true">8.2.4.</strong> 运算符表达式</a></li><li class="chapter-item expanded "><a href="../expressions/grouped-expr.html"><strong aria-hidden="true">8.2.5.</strong> 分组表达式</a></li><li class="chapter-item expanded "><a href="../expressions/array-expr.html"><strong aria-hidden="true">8.2.6.</strong> 数组和索引表达式</a></li><li class="chapter-item expanded "><a href="../expressions/tuple-expr.html"><strong aria-hidden="true">8.2.7.</strong> 元组和索引表达式</a></li><li class="chapter-item expanded "><a href="../expressions/struct-expr.html"><strong aria-hidden="true">8.2.8.</strong> 结构体表达式</a></li><li class="chapter-item expanded "><a href="../expressions/call-expr.html"><strong aria-hidden="true">8.2.9.</strong> 调用表达式</a></li><li class="chapter-item expanded "><a href="../expressions/method-call-expr.html"><strong aria-hidden="true">8.2.10.</strong> 方法调用表达式</a></li><li class="chapter-item expanded "><a href="../expressions/field-expr.html"><strong aria-hidden="true">8.2.11.</strong> 字段访问表达式</a></li><li class="chapter-item expanded "><a href="../expressions/closure-expr.html"><strong aria-hidden="true">8.2.12.</strong> 闭包表达式</a></li><li class="chapter-item expanded "><a href="../expressions/loop-expr.html"><strong aria-hidden="true">8.2.13.</strong> 循环表达式</a></li><li class="chapter-item expanded "><a href="../expressions/range-expr.html"><strong aria-hidden="true">8.2.14.</strong> 区间表达式</a></li><li class="chapter-item expanded "><a href="../expressions/if-expr.html"><strong aria-hidden="true">8.2.15.</strong> if 和 if let 表达式</a></li><li class="chapter-item expanded "><a href="../expressions/match-expr.html"><strong aria-hidden="true">8.2.16.</strong> 匹配表达式</a></li><li class="chapter-item expanded "><a href="../expressions/return-expr.html"><strong aria-hidden="true">8.2.17.</strong> 返回表达式</a></li><li class="chapter-item expanded "><a href="../expressions/await-expr.html"><strong aria-hidden="true">8.2.18.</strong> 等待(await)表达式</a></li></ol></li></ol></li><li class="chapter-item expanded "><a href="../patterns.html"><strong aria-hidden="true">9.</strong> 模式</a></li><li class="chapter-item expanded "><a href="../type-system.html"><strong aria-hidden="true">10.</strong> 类型系统</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../types.html"><strong aria-hidden="true">10.1.</strong> 类型</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../types/boolean.html"><strong aria-hidden="true">10.1.1.</strong> 布尔型</a></li><li class="chapter-item expanded "><a href="../types/numeric.html"><strong aria-hidden="true">10.1.2.</strong> 数字型</a></li><li class="chapter-item expanded "><a href="../types/textual.html"><strong aria-hidden="true">10.1.3.</strong> 字符型</a></li><li class="chapter-item expanded "><a href="../types/never.html"><strong aria-hidden="true">10.1.4.</strong> never类型</a></li><li class="chapter-item expanded "><a href="../types/tuple.html"><strong aria-hidden="true">10.1.5.</strong> 元组</a></li><li class="chapter-item expanded "><a href="../types/array.html"><strong aria-hidden="true">10.1.6.</strong> 数组</a></li><li class="chapter-item expanded "><a href="../types/slice.html"><strong aria-hidden="true">10.1.7.</strong> 切片</a></li><li class="chapter-item expanded "><a href="../types/struct.html"><strong aria-hidden="true">10.1.8.</strong> 结构体</a></li><li class="chapter-item expanded "><a href="../types/enum.html"><strong aria-hidden="true">10.1.9.</strong> 枚举</a></li><li class="chapter-item expanded "><a href="../types/union.html"><strong aria-hidden="true">10.1.10.</strong> 联合体</a></li><li class="chapter-item expanded "><a href="../types/function-item.html"><strong aria-hidden="true">10.1.11.</strong> 函数项类型</a></li><li class="chapter-item expanded "><a href="../types/closure.html"><strong aria-hidden="true">10.1.12.</strong> 闭包</a></li><li class="chapter-item expanded "><a href="../types/pointer.html"><strong aria-hidden="true">10.1.13.</strong> 指针型</a></li><li class="chapter-item expanded "><a href="../types/function-pointer.html"><strong aria-hidden="true">10.1.14.</strong> 函数指针</a></li><li class="chapter-item expanded "><a href="../types/trait-object.html"><strong aria-hidden="true">10.1.15.</strong> trait对象</a></li><li class="chapter-item expanded "><a href="../types/impl-trait.html"><strong aria-hidden="true">10.1.16.</strong> 实现trait</a></li><li class="chapter-item expanded "><a href="../types/parameters.html"><strong aria-hidden="true">10.1.17.</strong> 类型参数</a></li><li class="chapter-item expanded "><a href="../types/inferred.html"><strong aria-hidden="true">10.1.18.</strong> 推断型</a></li></ol></li><li class="chapter-item expanded "><a href="../dynamically-sized-types.html"><strong aria-hidden="true">10.2.</strong> 动态尺寸类型(DST)</a></li><li class="chapter-item expanded "><a href="../type-layout.html"><strong aria-hidden="true">10.3.</strong> 类型布局 </a></li><li class="chapter-item expanded "><a href="../interior-mutability.html"><strong aria-hidden="true">10.4.</strong> 内部可变性</a></li><li class="chapter-item expanded "><a href="../subtyping.html"><strong aria-hidden="true">10.5.</strong> 子类型和型变</a></li><li class="chapter-item expanded "><a href="../trait-bounds.html"><strong aria-hidden="true">10.6.</strong> trait约束及其生存期约束</a></li><li class="chapter-item expanded "><a href="../type-coercions.html"><strong aria-hidden="true">10.7.</strong> 类型自动强转</a></li><li class="chapter-item expanded "><a href="../destructors.html"><strong aria-hidden="true">10.8.</strong> 析构函数</a></li><li class="chapter-item expanded "><a href="../lifetime-elision.html"><strong aria-hidden="true">10.9.</strong> 生存期省略</a></li></ol></li><li class="chapter-item expanded "><a href="../special-types-and-traits.html"><strong aria-hidden="true">11.</strong> 特殊类型和 trait</a></li><li class="chapter-item expanded "><a href="../names.html"><strong aria-hidden="true">12.</strong> 名称</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../names/namespaces.html"><strong aria-hidden="true">12.1.</strong> 命名空间</a></li><li class="chapter-item expanded "><a href="../names/scopes.html"><strong aria-hidden="true">12.2.</strong> 作用域</a></li><li class="chapter-item expanded "><a href="../names/preludes.html"><strong aria-hidden="true">12.3.</strong> 预导入包</a></li><li class="chapter-item expanded "><a href="../paths.html"><strong aria-hidden="true">12.4.</strong> 路径</a></li><li class="chapter-item expanded "><a href="../names/name-resolution.html"><strong aria-hidden="true">12.5.</strong> 名称解析</a></li><li class="chapter-item expanded "><a href="../visibility-and-privacy.html"><strong aria-hidden="true">12.6.</strong> 可见性与隐私权</a></li></ol></li><li class="chapter-item expanded "><a href="../memory-model.html"><strong aria-hidden="true">13.</strong> 内存模型</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../memory-allocation-and-lifetime.html"><strong aria-hidden="true">13.1.</strong> 内存分配和生存期</a></li><li class="chapter-item expanded "><a href="../variables.html"><strong aria-hidden="true">13.2.</strong> 变量</a></li></ol></li><li class="chapter-item expanded "><a href="../linkage.html"><strong aria-hidden="true">14.</strong> 链接(linkage)</a></li><li class="chapter-item expanded "><a href="../unsafety.html"><strong aria-hidden="true">15.</strong> 非安全性</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../unsafe-functions.html"><strong aria-hidden="true">15.1.</strong> 非安全函数</a></li><li class="chapter-item expanded "><a href="../unsafe-blocks.html"><strong aria-hidden="true">15.2.</strong> 非安全代码块</a></li><li class="chapter-item expanded "><a href="../behavior-considered-undefined.html"><strong aria-hidden="true">15.3.</strong> 未定义行为</a></li><li class="chapter-item expanded "><a href="../behavior-not-considered-unsafe.html"><strong aria-hidden="true">15.4.</strong> 不被认为是非安全的行为</a></li></ol></li><li class="chapter-item expanded "><a href="../const_eval.html"><strong aria-hidden="true">16.</strong> 常量求值</a></li><li class="chapter-item expanded "><a href="../abi.html"><strong aria-hidden="true">17.</strong> ABI</a></li><li class="chapter-item expanded "><a href="../runtime.html"><strong aria-hidden="true">18.</strong> Rust运行时</a></li><li class="chapter-item expanded "><a href="../appendices.html"><strong aria-hidden="true">19.</strong> 附录</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../macro-ambiguity.html"><strong aria-hidden="true">19.1.</strong> 宏定义规范</a></li><li class="chapter-item expanded "><a href="../influences.html"><strong aria-hidden="true">19.2.</strong> 影响来源</a></li><li class="chapter-item expanded "><a href="../glossary.html"><strong aria-hidden="true">19.3.</strong> 术语表</a></li><li class="chapter-item expanded "><a href="../本书术语翻译对照表.html"><strong aria-hidden="true">19.4.</strong> 本书术语翻译对照表</a></li></ol></li></ol>
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                        <h1><a class="header" href="#modules" id="modules">Modules</a></h1>
<h1><a class="header" href="#模块" id="模块">模块</a></h1>
<blockquote>
<p><a href="https://github.com/rust-lang/reference/blob/master/src/items/modules.md">modules.md</a><br />
commit: eabdf09207bf3563ae96db9d576de0758c413d5d <br />
本章译文最后维护日期：2021-1-24</p>
</blockquote>
<blockquote>
<p><strong><sup>句法:</sup></strong><br />
<em>Module</em> :<br />
      <code>unsafe</code><sup>?</sup> <code>mod</code> <a href="../identifiers.html">IDENTIFIER</a> <code>;</code><br />
   | <code>unsafe</code><sup>?</sup> <code>mod</code> <a href="../identifiers.html">IDENTIFIER</a> <code>{</code><br />
        <a href="../attributes.html"><em>InnerAttribute</em></a><sup>*</sup><br />
        <a href="../items.html"><em>Item</em></a><sup>*</sup><br />
      <code>}</code></p>
</blockquote>
<p>模块是零个或多个<a href="../items.html">程序项</a>的容器。</p>
<p><em>模块项</em>是一个用花括号括起来的，有名称的，并以关键字 <code>mod</code> 作为前缀的模块。模块项将一个新的具名模块引入到组成 crate 的模块树中。模块可以任意嵌套。</p>
<p>模块的一个例子：</p>
<pre><pre class="playground"><code class="language-rust edition2018">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>mod math {
    type Complex = (f64, f64);
    fn sin(f: f64) -&gt; f64 {
        /* ... */
<span class="boring">      unimplemented!();
</span>    }
    fn cos(f: f64) -&gt; f64 {
        /* ... */
<span class="boring">      unimplemented!();
</span>    }
    fn tan(f: f64) -&gt; f64 {
        /* ... */
<span class="boring">      unimplemented!();
</span>    }
}
<span class="boring">}
</span></code></pre></pre>
<p>模块和类型共享相同的命名空间。禁止在同一个作用域中声明与此作用域下模块同名的具名类型(named type)：也就是说，类型定义、trait、结构体、枚举、联合体、类型参数或 crate 不能在其作用域中屏蔽此作用域中也生效的模块名称，反之亦然。使用 <code>use</code> 引入到当前作用域的程序项也受这个限制。</p>
<p>在句法上，关键字 <code>unsafe</code> 允许出现在关键字 <code>mod</code> 之前，但是在语义层面却会被弃用。这种设计允许宏在将关键字 <code>unsafe</code> 从 token流中移除之前利用此句法来使用此关键字。</p>
<h2><a class="header" href="#module-source-filenames" id="module-source-filenames">Module Source Filenames</a></h2>
<h2><a class="header" href="#模块的源文件名" id="模块的源文件名">模块的源文件名</a></h2>
<p>没有代码体的模块是从外部文件加载的。当模块没有 <code>path</code> 属性限制时，文件的路径和逻辑上的<a href="../paths.html">模块路径</a>互为镜像。祖先模块的路径组件(path component)是此模块文件的目录，而模块的内容存在一个以该模块名为文件名，以 <code>.rs</code> 为扩展文件名的文件中。例如，下面的示例可以反映这种模块结构和文件系统结构相互映射的关系：</p>
<table><thead><tr><th>模块路径</th><th>文件系统路径</th><th>文件内容</th></tr></thead><tbody>
<tr><td><code>crate</code></td><td><code>lib.rs</code></td><td><code>mod util;</code></td></tr>
<tr><td><code>crate::util</code></td><td><code>util.rs</code></td><td><code>mod config;</code></td></tr>
<tr><td><code>crate::util::config</code></td><td><code>util/config.rs</code></td><td></td></tr>
</tbody></table>
<p>当一个目录下有一个名为 <code>mod.rs</code> 的源文件时，模块的文件名也可以和这个目录互相映射。上面的例子也可以用一个承载同一源码内容的名为 <code>util/mod.rs</code> 的实体文件来表达模块路径 <code>crate::util</code>。注意不允许 <code>util.rs</code> 和 <code>util/mod.rs</code> 同时存在。</p>
<blockquote>
<p><strong>注意</strong>：在<code>rustc</code> 1.30 版本之前，使用文件 <code>mod.rs</code> 是加载嵌套子模块的方法。现在鼓励使用新的命名约定，因为它更一致，并且可以避免在项目中搞出许多名为 <code>mod.rs</code> 的文件。</p>
</blockquote>
<h3><a class="header" href="#the-path-attribute" id="the-path-attribute">The <code>path</code> attribute</a></h3>
<h3><a class="header" href="#path属性" id="path属性"><code>path</code>属性</a></h3>
<p>用于加载外部文件模块的目录和文件可以受 <code>path</code>属性的影响。（或者说可以联合使用 <code>path</code>属性来重新指定那种没有代码体的模块声明的加载对象的文件路径。）</p>
<p>对于不在内联模块(inline module)块内的模块上的 <code>path</code>属性，此属性引入的文件的路径为相对于当前源文件所在的目录。例如，下面的代码片段将使用基于其所在位置的路径:</p>
<!-- ignore: requires external files -->
<pre><code class="language-rust ignore">#[path = &quot;foo.rs&quot;]
mod c;
</code></pre>
<table><thead><tr><th>Source File</th><th><code>c</code>'s File Location</th><th><code>c</code>'s Module Path</th></tr></thead><tbody>
<tr><td><code>src/a/b.rs</code></td><td><code>src/a/foo.rs</code></td><td><code>crate::a::b::c</code></td></tr>
<tr><td><code>src/a/mod.rs</code></td><td><code>src/a/foo.rs</code></td><td><code>crate::a::c</code></td></tr>
</tbody></table>
<p>对于处在内联模块块内的 <code>path</code>属性，此属性引入的文件的路径取决于 <code>path</code>属性所在的源文件的类型。（先对源文件进行分类，）“mod-rs”源文件是根模块（比如是 <code>lib.rs</code> 或 <code>main.rs</code>）和文件名为 <code>mod.rs</code> 的模块，“非mod-rs”源文件是所有其他模块文件。（那）在 mod-rs 文件中，内联模块块内的 <code>path</code> 属性（引入的文件的）路径是相对于 mod-rs 文件的目录（该目录包括作为目录的内联模块组件名）。对于非mod-rs 文件，除了路径以此模块名为目录前段外，其他是一样的。例如，下面的代码片段将使用基于其所在位置的路径：</p>
<!-- ignore: requires external files -->
<pre><code class="language-rust ignore">mod inline {
    #[path = &quot;other.rs&quot;]
    mod inner;
}
</code></pre>
<table><thead><tr><th>Source File</th><th><code>inner</code>'s File Location</th><th><code>inner</code>'s Module Path</th></tr></thead><tbody>
<tr><td><code>src/a/b.rs</code></td><td><code>src/a/b/inline/other.rs</code></td><td><code>crate::a::b::inline::inner</code></td></tr>
<tr><td><code>src/a/mod.rs</code></td><td><code>src/a/inline/other.rs</code></td><td><code>crate::a::inline::inner</code></td></tr>
</tbody></table>
<p>在内联模块和其内嵌模块上混合应用上述 <code>path</code>属性规则的一个例子（mod-rs 和非mod-rs 文件都适用）：</p>
<!-- ignore: requires external files -->
<pre><code class="language-rust ignore">#[path = &quot;thread_files&quot;]
mod thread { // 译者注：有模块要内联进来的内联模块
    // 从相对于当前源文件的目录下的 `thread_files/tls.rs` 文件里载 `local_data` 模块。
    #[path = &quot;tls.rs&quot;]
    mod local_data; // 译者注：内嵌模块
}
</code></pre>
<h2><a class="header" href="#attributes-on-modules" id="attributes-on-modules">Attributes on Modules</a></h2>
<h2><a class="header" href="#模块上的属性" id="模块上的属性">模块上的属性</a></h2>
<p>模块和所有程序项一样能接受外部属性。它们也能接受内部属性：可以在带有代码体的模块的 <code>{</code> 之后，也可以在模块源文件的开头（但须在可选的 BOM 和 shebang 之后）。</p>
<p>在模块中有意义的内置属性是 <a href="../conditional-compilation.html"><code>cfg</code></a>、<a href="../attributes/diagnostics.html#the-deprecated-attribute"><code>deprecated</code></a>、<a href="https://doc.rust-lang.org/rustdoc/the-doc-attribute.html"><code>doc</code></a>、<a href="../attributes/diagnostics.html#lint-check-attributes">lint检查类属性</a>、<a href="#the-path-attribute"><code>path</code></a> 和 <a href="../names/preludes.html#the-no_implicit_prelude-attribute"><code>no_implicit_prelude</code></a>。模块也能接受宏属性。</p>
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